Motorized Wheel Chair Source

Short answer...yes she will be able to get on the rides.
Long answer...
After going to Six Flag Great America near Chicago with a friend who is in a wheelchair, I'm not sure you'll want to attempt it.
She has no use of her legs, but full use of her arms and no medical conditions that would prevent her from going on rides and uses a non-motorized wheelchair. Even though the park is wheelchair "accessible," I would hardly have called the staff or their policies friendly towards those who have needs other than those with two functioning legs.
First of all, you will need a special pass to get to the front of the line. Appeartly, the wheelchair is not a good indication that you need to have special access on the rides. And the pass was only good for the one in the wheelchair and one helper. So if you have a party of more than two people, I hope you like to be split up for the day.
Secondly, getting to the rides is doable. Many times it required going up the exits and even through some service entrances, but you can go it, but it was a tight fit. Once getting to the rides, it was a different story. Now this is only for the roller coasters as who really cares about the teacups, but the staff was completely not there to help. Remember the thing about one person only for the pass, yeah, it was a problem sometimes at this point as some of the seats are VERY awkward to get into and none of the staff was inclined or willing or were told not to help with moving handicapped patrons onto the rides. Other patrons helped (yea other patrons!) and that is what got through some of the rides. But really, the hardest part of some of it was the getting out of the ride.
Finally, keep in mind that some of the roller coasters will not be accessible to those without the use of their legs at all. Such as Iron Wolf, Superman, and possibly even Batman. My friend was not comfortable with rides where her legs were not secured within a car. However, the staff made it an uncomfortable situation for her to make those decisions.
Over-all, it wasn't really the access that was the biggest issue, it was the customer service. They were not friendly, the policies were not posted anywhere, and the ticket-takers did not help out at all when first arriving.
If you would like a recommendation of two parks that are fantastic with serving the needs of people and parties in wheelchairs, consider Cedar Point, Ohio or any of the Disney Parks. Not sure where you live or what your budget is, but they are fantastic at recognizing and accommodating wheelchairs.
I hope this helps and that no matter where you go, you and your party have fun!